Glue bone tankage treatment



Patented Jan. 26, 1954 GLUE BONE TANKAGEVT-REATMENTV Everett N; Mortenson; Chicago," 11:, assignor to Swift &' Company, Chicago; 111 a corporation of Illinois Application May 12, 1950,-SjeriaLNo. 161,505

2 Claims:

The present invention relates generally to the treatment of the residue from bone glue manufacture and more particularly to an improved process for the removal and recovery of grease contained in such residue.

In normal bone glue manufacture, green or fresh bones from slaughtering operations are subjected to a repeated series of steam cooks and hot water soaks to obtain the glue in the form of light liquors which are, subsequently concentrated by evaporation to heavy liquors and then dried: to. a solid material. As lay-products vfrom bone glue: manufacture, there-are recovered talilow, greasaand bone tankage. The'fats' are, rendered; out" of the boneand adhering meaty tissue: in the courseof the steam cooks and. are drawn- 01f from the glue extraction vessel at intervals during the course of the glueextraction Opera'- tion. More fat is also. skimmed from the top, of;

the light liquors while they are held in receiving" tanks prior to evaporation. Following the. glue: extraction procedure, and after the finallight liquors have been drained 01f, the bone glue ex-: traction tanks contain a wet, greasy bone, tankage representing a residue from the original freshv bone minus the available glue materials andsoine oi the grease.

The primary purpose of the glue extraction operation is to obtain a maximum yield of gluesolids with ahigh gel strength and viscosity. In

order to attain these results, the cooking and. soaking procedure must be carried out within:

Dry Bone-Meal Analysis Percent Moisture .7 v 3. 00, Protein. 12.00 Total P20. l 28:00 Fat 12. 5 Residue. r 44-. 5

When. the, bonetankaee; ismremoved' from. the. glue. extraction.tanksitcomprisesa.wetprciduct,

containing 50 per. cent. ,or morewater and 1a: con:

slomerate. mixture. of. cooked. bones and meaty tie 5,5 filri ntdepthrso.thatithersupernatmthot. water;

sue withconsiderable fatasis apparent from the,

foregoing; analysis; This, mixture of watersoakedmaterial'consists of both large andsmall particles, varying; in size from, extremely small' bone finesland meaty materials to pieces of both, severalinches long, andjoneto tworinches in diameter: Because of the prolonged cooking procedure required; to obtain maximum glue yields,

the. resulting, bone is quite soft and can be easily crushedj tola powdenby hand or at most by the pressure appliediby stepping on the hardest pieces when pl'acedon a, concrete floor. As can be seen from thelforegoing thewet tankage is somewhat of" a heterogeneous massandnot at, all the clean bare pieces offbone: particles which itiis; normally imaginedresult from such a cooking'operation.

It is, of course, desirable that the occluded fat in the'bone' tankage be removed prior to drying. The bone mealfprepared' from degreasedtanlcage is'of a higher quality, and in addition the fat removed and recovered in a degreasing operation is of itself quite valuable;

It" is therefore an object of the present invention to provide a simple and eflicient method for the degreasing'of gluegbone tankage.

A further object ofthisinvention isto provide a method" for' the degreasing of glue bone tankage'which does'not require-.tnemuseof surface active agents or detergents;

Additional objects if not specifically pointed out herein will bereadily apparent to one skilled in the art-from the-following detailed description of" the invention:

The, drawing is-a di'agrammatical representation of" onetypeof apparatus which may be: used to" carry out the method of'the present-invention.

It has now been found that a simple" and effici'entremoval'off' occluded grease and fat from glue bone tankage' results when-the-wet tankage fromttheglue extraction tanksistreated with hot water within a specific temperature range and is agitated by any" suitable means to arelatively under a critical degree-of agitation. More specifi'cal-ly', the tankage is'passedf'through a hot water b'atl'rv held at a temperature 'between about andZOOF: and, whil'e passing' through saidbath,

to, the drawing, thetankage is fed from the bone lue extractiongtank 1.0. at a; moreror-less uniform: rate? into-tank; 1.2.x via a: feeder. conveyor'such as;

over the bone is appreciable, i. e., from a minimum of 6 inches to a maximum of 2 to 4 feet. The amount of submergence is not critical except in so far as it relates to minimizing surface turbulence, a factor which will be further discussed below.

Within tank 12 there is mounted a suitable agitator 13. This may be a rotating worm or screw conveyor, as illustrated, either of the usual smooth, helicoid type or one with notches cut into it to give more lifting action on the solid particles. A ribbon-type screw conveyor would also be very suitable. The agitator I3 performs a double duty, i. e., it conveys the bone tankage through the tank and also agitates the tankage to permit good circulation of water therethrough. The delike the degree of agitation, be maintained within well-defined limits. It should be within the range of about 180 to 200 F. at all times. If

a lower temperature is used the fat will not be removed satisfactorily from the voids of the tankage; e. g., water at 150 F. removes only 25-30 per cent of the grease that water at about 180-200 F. will release, while with a higher temperature gree of agitation is important to the success of the present invention. If the bone mass is too greatly agitated there will-be an undue amount of attrition. .If too many fine bone particles areproduced by the agitation they will soak up the fat as soon as it is freed and retain it in the tankage. It has also been found that with too great an agitation, the fat which is freed from the bone will be re-emulsified in the dilute protein solution and will not rise to the surface where it may be recovered. Likewise, if insuficient agitation and turbulence is imparted to the bone and water respectively, not enough laundering action is produced to give good fat removal. It is therefore important that the velocity of the agitationproducing means in the water be carefully controlled. A suitable velocity has been found to range from 0.5 to 2.0 feet per second (peripheral velocity of the agitator screw). The exact velocity will be dependent upon the depth of supernatant water, since by operating with an appreciable depth of water over the actual agitated mass of bone the turbulence effect on the floating fat is less pronounced. The degree of agitation therefore must be suflicient to liberate occluded fat from the voids of the tankage, but must also be controlled to minimize surface turbulence of the water. Therefore, with a minimum of 6 inches supernatant water, the velocity should also be at the minimum of 0.5 foot per second and with 4 feet of supernatant water, the velocity should approach the maximum of 2.0 feet per second.

To provide the desired speed for the agitator screw, any suitable control and driving means may be used. These are indicated in the drawing as a motor 14 and gear reducer 15.

The bone tankage after passing through the tank 52 (wherein it should require approximately 10 minutes under the conditions given) is removed from the tank by any suitable means such as the inclined conveyor l6 illustrated in the drawing. Provision should be made for draining of the washed tankage by using perforated flights on the conveyor and providing a perforated drain section as indicated at H. Following the draining, the tankage is transferred to conventional drying equipment (employing, for example, horizontal, jacketed tanks with internal agitators), and there dried for further processing into bone meal or the like.

The water used in the degreasing tank can circulate continuously at a more or less constant rate overflow to a suitable settling tank [8 where the fats can be skimmed off through line 19, settled sludge withdrawn intermittently through line to be dried'wit the degreased bone or, if

preferred, dried with higher potein-content tankages, and the excess recirculated water drawn oiT there'is danger that the temperature level at the point of heat application will be suiiiciently high for simmering or boiling to take place with its consequent excessive agitation due to ebullition. The higher temperatures will cause excessive emulsification of the released fat with consequent poor recovery of fat. It has been found that within the temperature range disclosed tallow and most fats in general have the least cohesive action towards solid surfaces.

The following examples are given for the purpose of illustration only and are not to be construed as a limitation on the scope of the present invention:

Example I usual series of cooks and washes with steam and 4' fed at the rate of about 1800 pounds per hour to the grease recovery apparatus illustrated in the drawing. The Water in washer tank I2 is held at about F. (the lower limit of the preferred temperature range), the depth of supernatant hot water above the tankage in tank I2 is about 6 inches, and the peripheral velocity of the agitator screw I3 is maintained at about 05 foot per second. Under these conditions, an hourly grease recovery of about 43 pounds per hour is obtained, or approximately 40 per cent recovery of the total grease contained in the tankage (i. e., based on feeding wet bone tankage containing 12 per cent fat on the dry basis) Example II Following the general procedure outlined in Example I and the preceding description of the apparatus in the drawing, but changing the temperature of the water in tank [2 to about 200 F., increasing the depth of submergence of the tankage in said tank from about 6 inches to about 4 feet, and increasing the peripheral velocity of the agitator screw to approximately 2 feet per second, an improvement in the amount of grease recovery is noted. Under these conditions, and based on an 1800 pound per hour feed of wet bone tankage containing 12 per cent fat on the dry basis, the grease recovery is approximately 50 per cent of total grease contained in the tankage, or about 5% pounds of grease per hour.

7 This method of degreasing may be modified slightly so as to apply to grease removal from other fat-bearing materials where the fat is more or less mechanically entrapped in voids and inverted crevices of the solid phase. The method is not limited to the apparatus disclosed but may be carried out by any suitable means.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A method for degreasing glue bone tankage having fat particles occluded therein, which comprises: conveying said tankage in a submerged state through a hot water zone maintained at atmospheric pressure and a temperature within the range of about 180 to 200 F.; agitating said tankage passing through said zone to a degree equivalent to that produced by an agitator having a peripheral velocity between 0.5 and 2.0 feet per second; removing the floating fat particles liberated from said tankage by said agitation; and then removing the degreased tankage from said zone.

2. A method for degreasing glue bone tankage and the like having fat particles occluded therein comprising: submerging said tankage within a container maintained at atmospheric pressure and beneath the surface of water having a temperature within the range of about 180 F. to about 200 F.; gently agitating said tankage beneath said water to liberate particles of fat occluded in the voids of said tankage, said agitation being insufiicient to cause substantial surface turbulence-of said water; removing the liberated fat particles from the surface of said water; and removing the degreased tankage from said container.

EVERETT N. MORTENSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 925,971 Wheelwright June 22, 1999 1,764,390 Cleary' June 17, 1930 1,842,693 Schwarz Jan. 26, 1932 2,193,871 Hanno Mar. 19, 1940 2,395,900 Mueller Mar. 5, 1946 

1. A METHOD FOR DEGREASING GLUE BONE TANKAGE HAVING FAT PARTICLES OCCLUDED THEREIN, WHICH COMPRISES: CONVEYING SAID TANKAGE IN A SUBMERGED STATE THROUGH A HOT WATER ZONE MAINTAINED AT ATMOSPHERIC PRESSURE AND A TEMPERATURE WITHIN THE RANGE OF ABOUT 180* TO 200* F., AGITATING SAID TANKAGE PASSAGE PASSING THROUGH SAID ZONE TO A DEGREE EQUIVALENT TO THAT PRODUCED BY AN AGITATOR HAVING A PERIPHERAL VELOCITY BETWEEN 0.5 AND 2.0 FEET PER SECOND; REMOVING THE FLOATING FAT PARTICLES LIBERATED FROM SAID TANKAGE BY SAID AGITION; AND THEN REMOVING THE DEGREASED TANKAGE FROM SAID ZONE. 